Load Migration Method, Apparatus, and System

ABSTRACT

A load migration method, apparatus, and system. The method includes obtaining, by a first controller, in a process of migrating a user equipment (UE) to the first controller from a second controller, a first temporary user identifier of the UE, the first temporary user identifier comprising a second identifier of the second controller, allocating, by the first controller, a second temporary user identifier to the UE, the second temporary user identifier comprising a first identifier of the first controller, transmitting, by the first controller, the second temporary user identifier to a database server for updating the first temporary user identifier by the second temporary user identifier, and sending, by the first controller to an external network element, the first identifier of the first controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/786,390, filed on Feb. 10, 2020, which is a continuation of U.S.patent application Ser. No. 16/233,858, filed on Dec. 27, 2018, now U.S.Pat. No. 10,602,381, which is a continuation of InternationalApplication No. PCT/CN2016/087510, filed on Jun. 28, 2016. All of theafore-mentioned patent applications are hereby incorporated by referenceherein in their entireties.

TECHNICAL FIELD

The present disclosure relates to the communications field, and inparticular, to a load migration method, apparatus, and system.

BACKGROUND

In the 3rd Generation Partnership Project (3GPP) protocol, a Long TermEvolution (LTE) system includes an access network and a SystemArchitecture Evolution (SAE) core network.

FIG. 1 is a schematic architectural diagram of an SAE core network in acontrol domain. An external network element 01, for example, an eNodeB(evolved NodeB), an AF (application function) entity, or a GW-U (GatewayUser-plane), may interact with each controller 03 in the control domainby using a network element selector (NES) 02. Each controller 03 isconnected to a database server 04. The database server 04 may beconfigured to store resource information such as subscription data andcontext data of all UEs (user equipment) in a current control domain.After receiving a user request initiated by UE and forwarded by thenetwork element selector 02, the controller 03 may interact with thedatabase server 04 to implement functions such as mobility management,session management, and charging and policy management. The networkelement selector 02 may select, based on a load status of eachcontroller 03 and a preconfigured load balancing policy, a controller 03having relatively low load to process the user request, to balance loadof all controllers 03 in the current control domain and implementoptimized utilization of resources in the current control domain.

However, when the load of all the controllers 03 is greater than a loadthreshold, the current control domain is overloaded. In this case, whenany UE initiates a new user request, the network element selector 02needs to wait for an idle controller 03 and then can allocate thecontroller 03 to the user request. This increases a communication delaybetween the UE and the SAE core network.

SUMMARY

Embodiments of the present disclosure provide a load migration method,apparatus, and system, so as to implement load migration across controldomains, thereby reducing a communication delay generated due tooverload of a current control domain, and realizing resource sharing andcoordination across the control domains.

The following technical solutions are used in the embodiments of thepresent disclosure to achieve the foregoing objectives.

According to a first aspect, an embodiment of the present disclosureprovides a load migration method, including the following. A sourcecontroller determines a to-be-migrated UE that needs to be migrated to adestination controller. A database server stores resource informationsuch as subscription data and context data of the to-be-migrated UE.Each piece of data related to the to-be-migrated UE in the subscriptiondata and the context data reflects a correspondence between theto-be-migrated UE and the source controller. Therefore, to migrate theto-be-migrated UE to the destination controller in a second controldomain, the source controller may update the resource information of theto-be-migrated UE in the database server. In this case, the updatedresource information includes a correspondence between theto-be-migrated UE and the destination controller. In addition, anexternal network element originally stores the correspondence betweenthe to-be-migrated UE and the source controller. That is, afterreceiving a user request of the to-be-migrated UE, the external networkelement forwards the user request to the source controller based on thecorrespondence. Therefore, the source controller further needs to sendan inter-domain update instruction to the external network element. Theinter-domain update instruction includes an identifier of theto-be-migrated UE and an identifier of the destination controller, sothat the external network element establishes the correspondence betweenthe to-be-migrated UE and the destination controller. In this way, afterthe external network element receives the user request of theto-be-migrated UE subsequently, because the controller in thecorrespondence has been changed to the destination controller, theexternal network element can forward the user request to the destinationcontroller based on the correspondence, so that the destinationcontroller replaces the source controller to process the user request,to implement a load migration process across control domains, therebyreducing a communication delay generated due to overload of a currentcontrol domain.

In a possible design, the determining, by a source controller,to-be-migrated UE that needs to be migrated to a destination controllerincludes receiving, by the source controller, a list of candidatecontrollers in the second control domain that is sent by a migrationscheduler, receiving, by the source controller, a user request sent byfirst UE, where the source controller is a controller in a first controldomain that receives the user request, then, determining, by the sourcecontroller, whether to use the first UE as the to-be-migrated UE, anddetermining, by the source controller, a candidate controller in thelist of candidate controllers as the destination controller ifdetermining that the first UE is used as the to-be-migrated UE.

That is, when load of the first control domain in which the sourcecontroller is located is relatively high, the source controller mayactively perform load migration on the UE when the UE initiates the userrequest to the source controller, to implement a load migration processof single UE.

In a possible design, the determining, by the source controller, whetherto use the first UE as the to-be-migrated UE includes obtaining, by thesource controller, at least one of location information of the first UE,a priority of the user request, and a type of a service requested by thefirst UE, and determining, by the source controller based on at leastone of the obtained location information of the first UE, priority ofthe user request, and type of the service, whether to use the first UEas the to-be-migrated UE.

In a possible design, the determining, by a source controller, ato-be-migrated UE that needs to be migrated to a destination controllerincludes sending, by the source controller to a migration scheduler, aquantity of candidate UEs that need to be migrated, so that themigration scheduler determines, in the second control domain, Ndestination controllers that can accept the candidate UEs, anddetermines a quantity of candidate UEs that can be accepted by eachdestination controller, where N is a natural number, receiving, by thesource controller from the migration scheduler, identifiers of the Ndestination controllers and the quantity of candidate UEs that can beaccepted by each destination controller, and determining, by the sourcecontroller in the candidate UEs for each destination controller,to-be-migrated UE corresponding to the destination controller.

In this way, when load of the first control domain is relatively high,the source controller in the first control domain may actively migratethe candidate UEs in batches to the second control domain havingrelatively low load, and the source controller may migrate a pluralityof UEs to another control domain at a time, thereby quickly reducingload pressure of the source controller.

In a possible design, the updating, by the source controller, resourceinformation of the to-be-migrated UE in a database server includessearching, by the source controller, the database server forsubscription data and context data of the to-be-migrated UE based on theidentifier of the to-be-migrated UE, allocating, by the sourcecontroller, a new user identifier to the to-be-migrated UE, andupdating, by the source controller in the subscription data and thecontext data, the identifier of the to-be-migrated UE to the new useridentifier, and updating a stored identifier of the source controller tothe identifier of the destination controller.

In a possible design, after the sending, by the source controller, aninter-domain update instruction to an external network element, themethod further includes allocating, by the source controller, adestination session index to be used in the second control domain to theto-be-migrated UE, where the destination session index is used toindicate a session identifier of a session between the to-be-migrated UEand the destination controller, and sending, by the source controller, asession index update instruction to the external network element, wherethe session index update instruction includes the destination sessionindex, so that the external network element updates a session index ofthe to-be-migrated UE to the destination session index. In this way,subsequently, the to-be-migrated UE may interact with the destinationcontroller in the second control domain by using the destination sessionindex.

In a possible design, after the sending, by the source controller, aninter-domain update instruction to an external network element, themethod further includes sending, by the source controller, an NES updateinstruction to a destination NES, where the NES update instructionincludes the identifier of the to-be-migrated UE and the identifier ofthe destination controller, so that the destination NES establishes thecorrespondence between the to-be-migrated UE and the destinationcontroller.

In this way, when receiving the user request of the to-be-migrated UEsubsequently, the external network element may first forward the userrequest to the destination NES. Then, the destination NES forwards theuser request to the destination controller based on the correspondencebetween the to-be-migrated UE and the destination controller. Finally,the destination controller replaces the source controller to process theuser request, thereby implementing the load migration process across thecontrol domains.

According to a second aspect, an embodiment of the present disclosureprovides a load migration method. The method includes obtaining, by adestination controller, a migration request sent by a source controller,where the migration request carries an identifier of a to-be-migratedUE, the source controller is a controller in a first control domain, andthe destination controller is a controller in a second control domain.The method includes updating, by the destination controller based on theidentifier of the to-be-migrated UE, resource information of theto-be-migrated UE in a database server, where the updated resourceinformation includes a correspondence between the to-be-migrated UE andthe destination controller. The method also includes sending, by thedestination controller, an inter-domain update instruction to anexternal network element, where the inter-domain update instructionincludes the identifier of the to-be-migrated UE and an identifier ofthe destination controller, so that the external network elementestablishes the correspondence between the to-be-migrated UE and thedestination controller.

In a possible design, the load migration system further includes amigration scheduler connected to both the source controller and thedestination controller, and the obtaining, by a destination controller,a migration request sent by a source controller includes receiving, bythe destination controller, a migration request forwarded by a migrationscheduler, where the migration request carries a list of candidate UEsthat need to be migrated in the first control domain, and the list ofcandidate UEs includes an identifier of each candidate UE, anddetermining, by the destination controller, the to-be-migrated UE in thelist of candidate UEs.

According to a third aspect, an embodiment of the present disclosureprovides a source controller. The source controller includes adetermining unit, configured to determine a to-be-migrated userequipment UE that needs to be migrated to a destination controller,where the destination controller is a controller in a second controldomain. The source controller also includes an update unit, configuredto update resource information of the to-be-migrated UE in a databaseserver, where the updated resource information includes a correspondencebetween the to-be-migrated UE and the destination controller, and thedatabase server is connected to both the source controller and thedestination controller. The source controller also includes a sendingunit, configured to send an inter-domain update instruction to anexternal network element, where the inter-domain update instructionincludes an identifier of the to-be-migrated UE and an identifier of thedestination controller.

In a possible design, the source controller further includes anobtaining unit. The obtaining unit is configured to receive a list ofcandidate controllers in the second control domain that is sent by amigration scheduler, and receive a user request sent by first UE, wherethe source controller is a controller in the first control domain thatreceives the user request. The determining unit is specificallyconfigured to determine whether to use the first UE as theto-be-migrated UE if the user request of the first UE is received, anddetermine a candidate controller in the list of candidate controllers asthe destination controller if determining that the first UE is used asthe to-be-migrated UE.

In a possible design, the obtaining unit is further configured to obtainat least one of location information of the first UE, a priority of theuser request, and a type of a service requested by the first UE. Thedetermining unit is specifically configured to determine, based on atleast one of the obtained location information of the first UE, priorityof the user request, and type of the service, whether to use the firstUE as the to-be-migrated UE.

In a possible design, the sending unit is further configured to send, toa migration scheduler, a quantity of candidate UEs that need to bemigrated, so that the migration scheduler determines, in the secondcontrol domain, N destination controllers that are allowed to accept thecandidate UEs, and determines a quantity of candidate UEs that eachdestination controller is allowed to accept, where N is a naturalnumber. The obtaining unit is configured to receive, from the migrationscheduler, identifiers of the N destination controllers and the quantityof candidate UEs that each destination controller is allowed to accept.The determining unit is specifically configured to determine, in thecandidate UEs for each destination controller, to-be-migrated UE thatthe destination controller is allowed to accept.

In a possible design, the update unit is specifically configured tosearch the database server for subscription data and context data of theto-be-migrated UE based on the identifier of the to-be-migrated UE,reallocate a user identifier to the to-be-migrated UE, and update, inthe subscription data and the context data, the identifier of theto-be-migrated UE to the reallocated user identifier, and update astored identifier of the source controller to the identifier of thedestination controller.

In a possible design, the source controller further includes anallocation unit, configured to allocate a destination session index tobe used in the second control domain to the to-be-migrated UE, where thedestination session index is used to indicate a session identifier of asession between the to-be-migrated UE and the destination controller.The sending unit is further configured to send a session index updateinstruction to the external network element, where the session indexupdate instruction includes the destination session index.

In a possible design, the sending unit is further configured to send anNES update instruction to a destination NES, where the NES updateinstruction includes the identifier of the to-be-migrated UE and theidentifier of the destination controller.

According to a fourth aspect, an embodiment of the present disclosureprovides a destination controller. The destination controller includesan obtaining unit, configured to obtain a migration request sent by asource controller, where the migration request carries an identifier ofa to-be-migrated user equipment UE, the source controller is acontroller in a first control domain, and the destination controller isa controller in a second control domain. The destination controller alsoincludes an update unit, configured to update resource information ofthe to-be-migrated UE in a database server based on the identifier ofthe to-be-migrated UE, where the updated resource information includes acorrespondence between the to-be-migrated UE and the destinationcontroller, and the database server is connected to both the sourcecontroller and the destination controller. The destination controlleralso includes a sending unit, configured to send an inter-domain updateinstruction to an external network element, where the inter-domainupdate instruction includes the identifier of the to-be-migrated UE andan identifier of the destination controller.

In a possible design, the destination controller further includes adetermining unit. The obtaining unit is specifically configured toreceive a migration request forwarded by a migration scheduler, wherethe migration request carries a list of candidate UEs that need to bemigrated in the first control domain, and the list of candidate UEsincludes an identifier of each candidate UE that needs to be migrated.The determining unit is configured to determine the to-be-migrated UE inthe list of candidate UEs.

According to a fifth aspect, an embodiment of the present disclosureprovides a source controller, including a processor, a memory, a bus,and a transceiver. The memory is configured to store a computerexecutable instruction, the processor is connected to the memory byusing the bus, and when the source controller runs, the processorexecutes the computer executable instruction stored in the memory, toenable the source controller to perform the load migration methodaccording to any design of the first aspect.

According to a sixth aspect, an embodiment of the present disclosureprovides a destination controller, including a processor, a memory, abus, and a transceiver. The memory is configured to store a computerexecutable instruction, the processor is connected to the memory byusing the bus, and when the destination controller runs, the processorexecutes the computer executable instruction stored in the memory, toenable the destination controller to perform the load migration methodaccording to any design of the second aspect.

According to a seventh aspect, an embodiment of the present disclosureprovides a load migration system. The system includes the sourcecontroller according to any design of the third aspect, the destinationcontroller according to any design of the fourth aspect, and a databaseserver connected to both the source controller and the destinationcontroller. The source controller is located in a first control domain,and the destination controller is located in a second control domaindifferent from the first control domain.

In a possible design, the system further includes a migration schedulerconnected to both the source controller and the destination controller.

In a possible design, the system further includes a source NES locatedin the first control domain and connected to the source controller, anda destination NES located in the second control domain and connected tothe destination controller.

According to an eighth aspect, an embodiment of the present disclosureprovides a computer storage medium, configured to store a computersoftware instruction used by the foregoing source controller. Thecomputer storage medium includes a program designed for the sourcecontroller for executing the foregoing aspects.

According to a ninth aspect, an embodiment of the present disclosureprovides a computer storage medium, configured to store a computersoftware instruction used by the foregoing destination controller. Thecomputer storage medium includes a program designed for the destinationcontroller for executing the foregoing aspects.

In the present disclosure, names of the source controller and thedestination controller do not constitute a limitation to devices orfunctional modules. During actual implementation, the devices or thefunctional modules may exist with other names. Various devices orfunctional modules shall fall within the scope defined by claims of thepresent disclosure and their equivalent technologies, provided thatfunctions of the various devices or functional modules are similar tofunctions of the devices or functional modules in the presentdisclosure.

In addition, for technical effects brought by any design manner of thesecond to the ninth aspects, refer to technical effects brought bydifferent design manners of the first aspect, and details are notdescribed herein again.

These or other aspects of the present disclosure are more concise andcomprehensible in descriptions of the following embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, the following brieflydescribes the accompanying drawings required for describing theembodiments or the prior art.

FIG. 1 is a schematic architectural diagram of an SAE core network in acontrol domain in the prior art;

FIG. 2 is a first schematic architectural diagram of a load migrationsystem according to an embodiment of the present disclosure;

FIG. 3 is a second schematic architectural diagram of a load migrationsystem according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a computer device accordingto an embodiment of the present disclosure;

FIG. 5 is a first schematic interaction diagram of a load migrationmethod according to an embodiment of the present disclosure;

FIG. 6 is a second schematic interaction diagram of a load migrationmethod according to an embodiment of the present disclosure;

FIG. 7 is a third schematic interaction diagram of a load migrationmethod according to an embodiment of the present disclosure;

FIG. 8 is a fourth schematic interaction diagram of a load migrationmethod according to an embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of a source controlleraccording to an embodiment of the present disclosure; and

FIG. 10 is a schematic structural diagram of destination controlleraccording to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following describes the technical solutions in the embodiments ofthe present disclosure with reference to the accompanying drawings inthe embodiments of the present disclosure. Apparently, the describedembodiments are merely some but not all of the embodiments of thepresent disclosure.

In addition, the terms “first” and “second” are merely intended for apurpose of description, and shall not be understood as an indication orimplication of relative importance or implicit indication of the numberof indicated technical features. Therefore, a feature limited by “first”or “second” may explicitly or implicitly include one or more features.In the descriptions of the present disclosure, “a plurality of” meanstwo or at least two unless otherwise stated.

The term “and/or” in this specification describes only an associationrelationship for describing associated objects and represents that threerelationships may exist. For example, A and/or B may represent thefollowing three cases: Only A exists, both A and B exist, and only Bexists. In addition, the character “/” in this specification generallyindicates an “or” relationship between the associated objects.

The embodiments of the present disclosure provide a load migrationmethod, which may be applied to a load migration system 100 including aplurality of control domains. When a control domain in the plurality ofcontrol domains is overloaded, one or more UEs (which are referred to asto-be-migrated UE in the embodiments of the present disclosure) may bemigrated to another control domain, and a controller in the anothercontrol domain processes a user request of the to-be-migrated UE,thereby reducing a communication delay generated due to overload of thecurrent control domain, and realizing resource sharing and coordinationacross control domains.

FIG. 2 is a schematic architectural diagram of the foregoing loadmigration system 100. The load migration system 100 includes at least afirst control domain and a second control domain. A plurality ofcontrollers are disposed in each of the first control domain and thesecond control domain. For example, controllers 21A are disposed in thefirst control domain and controllers 21B are disposed in the secondcontrol domain. All of the controllers are connected to a databaseserver (DB Server) 22. Optionally, one NES is disposed in each controldomain, namely, an NES 23A is disposed in the first control domain andan NES 23B is disposed in the second control domain.

The NES is configured to forward, to a corresponding controller in acurrent control domain, a user request sent by an external networkelement 24. The controller may interact with the database server 22, toimplement functions such as mobility management, session management, andcharging and policy management that are requested in the user request.In addition, resource information such as subscription data and contextdata of UE that is stored in the database server 22 may be shared acrosscontrol domains. The external network element 24 may be specifically adevice such as an eNodeB, an AF, or a GW-U. This is not limited in theembodiments of the present disclosure.

It should be noted that in the load migration method provided in theembodiments of the present disclosure, a controller needing to performload migration, for example, a controller in the first control domain,is referred to as a source controller, and a controller accepting theload migration, for example, a controller in the second control domain,is referred to as a destination controller. The source controller andthe destination controller are located in different control domains.

Similarly, a network element selector connected to the source controllermay be referred to as a source NES, and a network element selectorconnected to the destination controller may be referred to as adestination NES.

In this case, based on the load migration system wo, the embodiments ofthe present disclosure provide two load migration methods. In one loadmigration method, the source controller actively migrates ato-be-migrated UE in a control domain (for example, the first controldomain in the embodiments of the present disclosure) in which the sourcecontroller is located to the destination controller in the secondcontrol domain. In the other load migration method, the destinationcontroller actively migrates a to-be-migrated UE in a control domain inwhich the source controller is located to the destination controller.Both the two methods can implement load migration across controldomains, thereby reducing a communication delay generated due tooverload of a current control domain, and realizing resource sharing andcoordination across the control domains.

In the embodiments of the present disclosure, the migrating theto-be-migrated UE of the source controller to the destination controllermeans that a function of controlling the to-be-migrated UE is migratedto the destination controller. Details are not described again insubsequent embodiments.

Further, based on the load migration system 100 shown in FIG. 2, asshown in FIG. 3, a new network element, that is, a migration scheduler25, is further introduced into the load migration system 100 provided inthe embodiments of the present disclosure. The migration scheduler 25 isconnected to each controller in each control domain.

Specifically, the migration scheduler 25 may be configured to monitor aload status of each controller in each control domain, to calculate aload value of each control domain, thereby implementing load schedulingacross control domains based on load values of different controldomains. For example, when a load value of the first control domain isrelatively large and a load value of the second control domain isrelatively small, the migration scheduler 25 may send a migrationpermission message to a source controller in the first control domain,to trigger the source controller in the first control domain to enable aload migration function. In addition, the migration scheduler 25 mayfurther select an appropriate destination controller for the sourcecontroller, for example, select a controller having relatively low loadin the second control domain as the destination controller, and thedestination controller or the source controller migrates to-be-migratedUE to the destination controller.

It should be noted that the migration scheduler 25 may be integratedinto any one of the foregoing devices in a form of a functional module,or may implement the foregoing functions in a form of an independentphysical device. This is not limited in the embodiments of the presentdisclosure.

In the subsequent embodiments, the load migration method is described indetail with reference to the load migration system 100. Therefore,details are not described herein.

As shown in FIG. 4, the controller, the NES, or the migration scheduler25 in FIG. 2 and FIG. 3 may be implemented by a computer device (orsystem) in FIG. 4.

FIG. 4 is a schematic diagram of a computer device 100 according to anembodiment of the present disclosure. The computer device 100 includesat least one processor 11, a communications bus 12, a memory 13, and atleast one transceiver 14.

The processor 11 may be a general-purpose central processing unit (CPU),a microprocessor, an application-specific integrated circuit (ASIC), orone or more integrated circuits configured to control execution of aprogram in the solutions of the present disclosure.

The communications bus 12 may include a path for transmittinginformation between the foregoing components. The transceiver 14 is anapparatus using any type of transceiver, and is configured tocommunicate with another device or a communications network, such as theEthernet, a radio access network (RAN), or a wireless local area network(WLAN).

The memory 13 may be a read-only memory (ROM) or another type of staticstorage device that can store static information and a staticinstruction, or a random access memory (RAM) or another type of dynamicstorage device that can store information and an instruction, or may bean electrically erasable programmable read-only memory (EEPROM), acompact disc read-only memory (CD-ROM) or another compact disc storagemedium, optical disc storage medium (including a compact disc, a laserdisc, an optical disc, a digital versatile disc, a Blu-ray disc, or thelike) or magnetic disk storage medium, another magnetic storage device,or any other medium that can be configured to carry or store expectedprogram code in a form of an instruction or a data structure and that isaccessible by a computer, but is not limited thereto. The memory mayindependently exist and may be connected to the processor by using thecommunications bus. The memory may alternatively be integrated with theprocessor.

The memory 13 is configured to store application program code forexecuting the solutions of the present disclosure, and the processor 11controls execution. The processor 11 is configured to execute theapplication program code stored in the memory 13.

During specific implementation, in an embodiment, the processor 11 mayinclude one or more CPUs, for example, a CPU 0 and a CPU 1 in FIG. 4.

During specific implementation, in an embodiment, the computer device100 may include a plurality of processors, for example, two processors11 in FIG. 4. Each of these processors may be a single-core (single-CPU)processor, or may be a multi-core (multi-CPU) processor. Herein, theprocessor may be one or more devices, circuits, and/or processing coresconfigured to process data (for example, a computer programinstruction).

During specific implementation, in an embodiment, the computer deviceboo may further include an output device 15 and an input device 16. Theoutput device 15 communicates with the processor 11, and may displayinformation in various manners. For example, the output device 15 may bea liquid crystal display (LCD), a light emitting diode (LED) displaydevice, a cathode ray tube (CRT) display device, a projector, or thelike. The input device 16 communicates with the processor 11, and mayreceive an input of a user in various manners. For example, the inputdevice 16 may be a mouse, a keyboard, a touchscreen device, a sensingdevice, or the like.

The computer device 100 may be a general-purpose computer device or adedicated computer device. During specific implementation, the computerdevice 100 may be a desktop computer, a portable computer, a networkserver, a personal digital assistant (PDA), a mobile phone, a tabletcomputer, a wireless terminal device, a communications device, anembedded device, or a device having a structure similar to that in FIG.4. In this embodiment of the present disclosure, a type of the computerdevice 100 is not limited.

It should be noted that in the embodiments of the present disclosure,any functional node, for example, the controller, the NES, or themigration scheduler 25, in the system may be implemented by a physicaldevice, or may be implemented by a combination of a plurality ofphysical devices. A plurality of functional nodes in the system may beseparately implemented by different physical devices, or may beimplemented by a same physical device. It may be understood that anyfunctional node in the system may be a logical functional module in aphysical device, or may be a logical functional module including aplurality of physical devices.

Further, to clearly describe the load migration method provided in thepresent disclosure, descriptions are provided below all by using alogical functional module as an execution body. A person skilled in theart may understand that, during specific implementation, the logicalfunctional module needs to depend on a hardware resource of a physicaldevice in which the logical functional module is located.

In addition, in the embodiments of the present disclosure, the loadmigration system 100 may be applied to a 5G network or a Long TermEvolution (LTE) network, or may be applied to an LTE-Advancedcommunications network, for example, an LTE-A long term evolutionadvanced) system, and may further be applied to a 3rd Generation mobilecommunications (3G) network such as WCDMA. This is not limited in thepresent disclosure.

The load migration method provided in the embodiments of the presentdisclosure is described in detail below by using embodiments withreference to the load migration system 100 and different applicationscenarios.

Embodiment 1

This embodiment of the present disclosure provides a load migrationmethod. When a UE initiates a user request to a source controller byusing an external network element, the source controller may activelyperform load migration on the UE. The source controller is located in afirst control domain, a destination controller is located in a secondcontrol domain, and the first control domain and the second controldomain are different control domains. As shown in FIG. 5, the loadmigration method includes the following steps.

101. A migration scheduler obtains a first load value of the firstcontrol domain and a second load value of the second control domain.

102. If the first load value is greater than a first load threshold, andthe second load value is less than a second load threshold (where thefirst load threshold is greater than or equal to the second loadthreshold), the migration scheduler determines, in the second controldomain, a list of candidate controllers that can accept a to-be-migratedUE.

103. The migration scheduler sends a migration permission message to thesource controller, where the migration permission message carries thelist of candidate controllers.

104. The external network element forwards, to a controller in the firstcontrol domain, a user request sent by a first UE, where the controllerreceiving the user request in the first control domain is the sourcecontroller.

105. The source controller determines whether to use the first UE as theto-be-migrated UE.

106. The source controller determines a candidate controller in the listof candidate controllers as the destination controller if determiningthat the first UE is used as the to-be-migrated UE.

107. The source controller updates resource information of theto-be-migrated UE in a DB server, where the updated resource informationincludes a correspondence between the to-be-migrated UE and thedestination controller.

108. The source controller sends an inter-domain update instruction tothe external network element, where the inter-domain update instructionincludes an identifier of the to-be-migrated UE and an identifier of thedestination controller.

In this way, in the load migration method provided in this embodiment ofthe present disclosure, when the UE initiates the user request to thesource controller by using the external network element, the sourcecontroller may actively perform load migration on the UE. First, whenthe load value of the first control domain is relatively large, and theload value of the second control domain is relatively small, the sourcecontroller uses, as the to-be-migrated UE, a UE indicated by a newlyreceived user request. To migrate the to-be-migrated UE to thedestination controller in the second control domain, the sourcecontroller may update the resource information of the to-be-migrated UEin the DB server. The updated resource information includes thecorrespondence between the to-be-migrated UE and the destinationcontroller. In addition, the source controller further needs to send theinter-domain update instruction to the external network element, so thatthe external network element establishes the correspondence between theto-be-migrated UE and the destination controller. In this way, aftersubsequently receiving the user request of the to-be-migrated UE, theexternal network element can forward the user request to the destinationcontroller based on the correspondence, so that the destinationcontroller replaces the source controller to process the user request,to implement a load migration process across control domains, therebyreducing a communication delay generated due to overload of a currentcontrol domain, and realizing resource sharing and coordination acrossthe control domains.

For example, in step 101, because the migration scheduler may establisha data connection to each controller in each control domain, themigration scheduler can obtain a load value of each controller in eachcontrol domain. For example, ten controllers in the first control domainmay periodically report current load values of the controllers to themigration scheduler. Alternatively, the migration scheduler may activelyquery a current load value of each controller separately from tencontrollers in the first control domain. In this way, the migrationscheduler can determine the first load value of the first control domainbased on a load value of each controller in the first control domain.

For example, the migration scheduler may perform weighted averaging onload values of all controllers in the first control domain, to calculatethe first load value of the first control domain.

Similarly, the migration scheduler may further determine the second loadvalue of the second control domain based on a load value of eachcontroller in the second control domain.

In step 102, the migration scheduler may compare an obtained load valueof each control domain, to determine an overloaded control domain orsome overloaded control domains (that is, determining a source controldomain that needs to perform load migration), and determine whether acontrol domain (that is, a destination control domain) having relativelylow load exists to replace the source control domain to process a userrequest or user requests that are of one or more UEs (that is, theto-be-migrated UE) and that originally need to be processed by thesource control domain.

Specifically, if the first load value is greater than the first loadthreshold, and the second load value is less than the second loadthreshold, which indicates that the first control domain has relativelyhigh load and needs to perform load migration, and the second controldomain that can accept the load migration exists, the migrationscheduler determines, in the second control domain, the list ofcandidate controllers that can receive the to-be-migrated UE.

For example, the migration scheduler may use X controllers in the secondcontrol domain that have smallest load values as candidate controllers,to obtain a list of candidate controllers including the X candidatecontrollers.

For example, the list of candidate controllers includes an identifier ofthe second control domain and an identifier of each candidatecontroller.

Then, in step 103, the migration scheduler may send the migrationpermission message to all controllers in the first control domain, thatis, inform all the controllers in the first control domain that a loadmigration function can subsequently be performed.

The migration permission message carries the list of candidatecontrollers, so that a controller receiving the migration permissionmessage determines a destination controller of the load migration.

Subsequently, when a UE, for example the first UE, that originallybelongs to the first control domain sends a user request to the externalnetwork element, the external network element still stores acorrespondence between the first UE and the first control domain in thiscase. Therefore, in step 104, the external network element stillforwards the user request of the first UE to a controller, that is, thesource controller, in the first control domain as in an existinginteraction procedure.

Herein, a network element selector is disposed in each control domain,and the network element selector may be configured to forward, to acorresponding controller in the current control domain, each userrequest sent by the external network element. Therefore, the externalnetwork element may first send, to a network element selector in thefirst control domain, the user request sent by the first UE. Then, thenetwork element selector forwards, based on a pre-stored correspondencebetween the first UE and a controller in the first control domain, theuser request to the controller, that is, the source controller,indicated by the correspondence.

Then, in step 105, the source controller receiving the user requestdetermines whether to use the first UE as the to-be-migrated UE.

For example, when a current load value of the source controller isgreater than a load threshold, the first UE may be determined as theto-be-migrated UE.

Alternatively, to enable load migration to be performed more properly,the source controller may first obtain at least one of locationinformation of the first UE, a priority of the user request, and aservice type in the user request. The location information of the firstUE, the priority of the user request, or the service type in the userrequest may be carried in the user request. Then, the source controllerdetermines, based on at least one of the obtained location informationof the first UE, priority of the user request, and service type in theuser request, whether to use the first UE as the to-be-migrated UE.

For example, for a user request having a relatively high priority, whenload migration is performed, a security risk and a communication delayof the user request may be increased. Therefore, when a priority of theuser request of the first UE is relatively high, a subsequent loadmigration procedure is not triggered. When a priority of the userrequest of the first UE is relatively low, the first UE may be used asthe to-be-migrated UE, and step 106 to step 108 may be performed.

In step 106, if determining that the first UE is used as theto-be-migrated UE, the source controller may determine, in the list ofcandidate controllers that is obtained in step 103, a candidatecontroller in the second control domain as the destination controller.

For example, the source controller may use a candidate controller havinga lowest load in the list of candidate controllers as the destinationcontroller. In this case, to prevent other controllers in the firstcontrol domain from selecting the same candidate controller as thedestination controller, the source controller may send an occupationmessage to the other controllers in the first control domain. Theoccupation message includes an identifier of the candidate controllerselected by the source controller, to avoid a load surge caused becausethe candidate controller accepts an excessively large quantity ofto-be-migrated UEs.

Then, in step 107, because the DB server has stored the resourceinformation such as subscription data and context data of theto-be-migrated UE, and each piece of data related to the to-be-migratedUE in the subscription data and the context data reflects acorrespondence between the to-be-migrated UE and the source controller.Therefore, to migrate the to-be-migrated UE to the destinationcontroller in the second control domain to implement load migration, thesource controller may update the resource information of theto-be-migrated UE in the DB server.

For example, a temporary user identifier of the to-be-migrated UE isstored in the subscription data and the context data of theto-be-migrated UE, where the temporary user identifier includes anidentifier of the source controller, for example, an MMEI (mobilitymanagement entity identifier) of the source controller. In this case, instep 107, the source controller may reallocate a new temporary useridentifier to the to-be-migrated UE. Because the source controller hasdetermined the destination controller that is to accept theto-be-migrated UE, the reallocated new temporary user identifier maycarry the identifier of the destination controller. Then, the sourcecontroller replaces, in the DB server, the temporary user identifieralready stored in the subscription data and the context data of theto-be-migrated UE with the new temporary user identifier, to establishthe correspondence between the to-be-migrated UE and the destinationcontroller in the subscription data and the context data of theto-be-migrated UE.

In addition, because the external network element originally stores thecorrespondence between the to-be-migrated UE and the source controller,after receiving the user request of the to-be-migrated UE, the externalnetwork element forwards the user request to the source controller basedon the correspondence. Therefore, in step 108, to migrate theto-be-migrated UE to the destination controller in the second controldomain to implement load migration, the source controller further needsto send the inter-domain update instruction to the external networkelement. The inter-domain update instruction includes the identifier ofthe to-be-migrated UE and the identifier of the destination controller,so that the external network element establishes the correspondencebetween the to-be-migrated UE and the destination controller accordingto the inter-domain update instruction.

Specifically, the source controller may send an S1-AP UE ID (that is, aUE identifier of an S1 interface) and the identifier of the destinationcontroller to the external network element, and the external networkelement stores the S1-AP UE ID and the identifier of the destinationcontroller in a storage unit of the external network element in a formof a list, to establish the correspondence between the to-be-migrated UEand the destination controller. Certainly, the external network elementmay further store an identifier of a network element selector (that is,a destination network element selector) in the second control domain inthe foregoing list.

In this way, after the external network element receives the userrequest of the to-be-migrated UE subsequently, the correspondencebetween the to-be-migrated UE and the source controller has been changedto the correspondence between the to-be-migrated UE and the destinationcontroller. Therefore, the external network element can forward the userrequest to the destination controller based on the foregoing changedcorrespondence, so that the destination controller replaces the sourcecontroller to process the user request, thereby implementing a loadmigration process across control domains.

Optionally, still as shown in FIG. 5, a session index needs to be usedto identify an identity of UE when the UE has a session with acontroller to which the UE belongs. For example, the session index maybe a GUTI (globally unique temporary identity), an IP address, or thelike. Therefore, when different session indexes are used in differentcontrol domains, step 109 further needs to be performed. That is, thesource controller allocates a destination session index to be used inthe second control domain to the to-be-migrated UE, in other words,allocates a new session index to the to-be-migrated UE. The destinationsession index is used to indicate a session identifier of a sessionbetween the to-be-migrated UE and the destination controller.

Then, in step 110, the source controller sends a session index updateinstruction to the external network element, where the session indexupdate instruction carries the newly allocated destination sessionindex, so that the external network element updates a stored sessionindex of the to-be-migrated UE to the destination session index. In thisway, subsequently, the to-be-migrated UE may interact with thedestination controller in the second control domain by using thedestination session index.

Herein, it should be noted that in step no, a process of instructing, bythe source controller, the external network element to update thedestination session index may be explicit or implicit. For example, thesource controller may directly send the session index update instructioncarrying the destination session index to the external network element,that is, explicitly instruct the external network element to update thesession index of the to-be-migrated UE. Alternatively, in a normalprocess of interacting with the external network element, the sourcecontroller may add the destination session index to some responsemessages, for example, a TAU (Tracking Area Update) accept message, toimplicitly trigger the process of updating the destination session indexby the external network element.

In addition, if a network element selector (that is, the destinationNES) is disposed in the second control domain, optionally, because theto-be-migrated UE does not belong to the second control domain beforethe load migration, the destination NES does not record thecorrespondence between the to-be-migrated UE and the destinationcontroller. In this case, still as shown in FIG. 5, the sourcecontroller may further perform step 111. That is, the source controllersends an NES update instruction to the destination NES, where the NESupdate instruction also carries the identifier of the to-be-migrated UEand the identifier of the destination controller, so that thedestination NES establishes the correspondence between theto-be-migrated UE and the destination controller.

In this way, when subsequently receiving the user request of theto-be-migrated UE, the external network element may first forward theuser request to the destination NES. Then, the destination NES forwardsthe user request to the destination controller based on thecorrespondence between the to-be-migrated UE and the destinationcontroller. Finally, the destination controller replaces the sourcecontroller to process the user request, thereby implementing the loadmigration process across the control domains.

Alternatively, when the user request forwarded by the external networkelement to the destination NES has carried the correspondence betweenthe to-be-migrated UE and the destination controller, for example, theforegoing new temporary user identifier reallocated by the sourcecontroller to the to-be-migrated UE carries the identifier of thedestination controller, step 111 does not need to be performed. Thedestination NES may directly forward the user request to thecorresponding destination controller based on the correspondence betweenthe to-be-migrated UE and the destination controller that is carried inthe user request.

Further, by performing step 107 to step in, the source controller hasmigrated the first UE to the destination controller in the secondcontrol domain. In this case, the destination controller may process theuser request of the first UE that is received by the external networkelement in step 104.

Certainly, subsequently, if determining that the load of the firstcontrol domain is lowered below a preset load migration threshold, themigration scheduler may further send a migration stop message to all thecontrollers in the first control domain. In this case, after receivingthe user request subsequently, any controller in the first controldomain does not trigger the load migration process in step 105 to step111.

Steps performed by the source controller in step 101 to step 111 may beimplemented by the source controller by executing the programinstruction stored in the memory 13 and executed by the processor 11 inFIG. 4. Similarly, steps performed by the destination controller in step101 to step 111 may be implemented by the destination controller byexecuting the program instruction stored in the memory 13 and executedby the processor 11 in FIG. 4.

Embodiment 2

This embodiment of the present disclosure provides a load migrationmethod. When a UE initiates a user request to a source controller byusing an external network element, a destination controller performsload migration on the UE. The source controller is located in a firstcontrol domain, and the destination controller is located in a secondcontrol domain different from the first control domain. As shown in FIG.6, the load migration method includes the following steps.

201. A migration scheduler obtains a first load value of the firstcontrol domain and a second load value of the second control domain.

202. If the first load value is greater than a first load threshold, andthe second load value is less than a second load threshold (where thefirst load threshold is greater than or equal to the second loadthreshold), the migration scheduler sends a migration permission messageto a controller in the first control domain, where the migrationpermission message is used to indicate that the controller in the firstcontrol domain may migrate a to-be-migrated UE from the first controldomain.

203. The external network element forwards, to a controller in the firstcontrol domain, a user request sent by a first UE, where the controllerreceiving the user request in the first control domain is the sourcecontroller.

204. The source controller determines whether to use the first UE as theto-be-migrated UE.

205. The source controller sends a migration request to the migrationscheduler if determining that the first UE is used as the to-be-migratedUE, where the migration request carries an identifier of theto-be-migrated UE.

206. The migration scheduler determines, based on a load value of eachcontroller in the second control domain, a destination controllerreceiving the migration request in the second control domain.

207. The migration scheduler forwards the migration request to thedestination controller.

208. The destination controller updates resource information of theto-be-migrated UE in a DB server based on the identifier of theto-be-migrated UE, where the updated resource information includes acorrespondence between the to-be-migrated UE and the destinationcontroller.

209. The destination controller sends an inter-domain update instructionto the external network element, where the inter-domain updateinstruction includes the identifier of the to-be-migrated UE and anidentifier of the destination controller.

In this way, in the load migration method provided in this embodiment ofthe present disclosure, when the UE initiates the user request to thesource controller by using the external network element, a partyaccepting load migration, that is, the destination controller, mayactively perform load migration on the UE. Specifically, when the loadvalue of the first control domain is relatively large, and the loadvalue of the second control domain is relatively small, the sourcecontroller adds the identifier of the to-be-migrated UE to the migrationrequest and sends the migration request to the destination controller.Then, the destination controller may update the resource information ofthe to-be-migrated UE in the DB server. The updated resource informationincludes the correspondence between the to-be-migrated UE and thedestination controller. In addition, the destination controller furtherneeds to send the inter-domain update instruction to the externalnetwork element, so that the external network element establishes thecorrespondence between the to-be-migrated UE and the destinationcontroller. In this way, after subsequently receiving the user requestof the to-be-migrated UE, the external network element can forward theuser request to the destination controller based on the correspondence,so that the destination controller replaces the source controller toprocess the user request, to implement a load migration process acrosscontrol domains, thereby reducing a communication delay generated due tooverload of a current control domain, and realizing resource sharing andcoordination across the control domains.

For example, in step 201, the migration scheduler may determine thefirst load value of the first control domain and the second load valueof the second control domain by using a monitored load value of eachcontroller in each control domain. For a specific method for determiningthe first load value of the first control domain and the second loadvalue of the second control domain, refer to step 101, and details arenot described herein again.

In step 202, if the first load value is greater than the first loadthreshold, and the second load value is less than the second loadthreshold, which indicates that the first control domain has relativelyhigh load and needs to perform load migration, and the second controldomain that can accept the load migration exists, the migrationscheduler may send the migration permission message to all controllersin the first control domain, that is, inform all the controllers in thefirst control domain that a load migration function can be performedsubsequently.

Subsequently, when a UE, for example the first UE, that originallybelongs to the first control domain sends a user request to the externalnetwork element, the external network element still stores acorrespondence between the first UE and the first control domain in thiscase. Therefore, in step 203, the external network element stillforwards the user request of the first UE to a controller, that is, thesource controller, in the first control domain as in an existinginteraction procedure.

Specifically, a network element selector, that is, a source NES, may bedisposed in the first control domain. The external network element mayfirst send, to the source NES, the user request sent by the first UE,and the source NES forwards the user request to a correspondingcontroller, that is, the source controller.

Then, in step 204, the source controller receiving the user requestdetermines whether to use the first UE as the to-be-migrated UE. For themethod, specifically refer to related descriptions in step 105, anddetails are not described herein again.

Further, in step 205, the source controller sends the migration requestto the migration scheduler if determining that the first UE is used asthe to-be-migrated UE. The migration request carries the identifier ofthe to-be-migrated UE, for example, an IMSI (international mobilesubscriber identity) of the to-be-migrated UE.

After the migration scheduler receives the migration request, becausethe migration scheduler has obtained the load value of each controllerin the second control domain having relatively low load in step 201, instep 206, the migration scheduler may select an appropriate destinationcontroller for the source controller based on the load value of eachcontroller in the second control domain.

For example, the second control domain is neighboring to the firstcontrol domain, and a controller A in the second control domain has asmallest load value. In this case, the migration scheduler may determinethe controller A as the destination controller. Subsequently, thecontroller A in the second control domain replaces the source controllerto process the user request of the to-be-migrated UE.

In this case, in step 207, the migration scheduler forwards, to thedestination controller determined in step 206, the migration requestsent by the source controller.

After receiving the migration request, in step 208, the destinationcontroller updates the resource information of the to-be-migrated UE inthe DB server based on the identifier of the to-be-migrated UE that iscarried in the migration request. The updated resource informationincludes the correspondence between the to-be-migrated UE and thedestination controller.

A method used by the destination controller to update the resourceinformation of the to-be-migrated UE in the DB server is similar to themethod used by the source controller to update the resource informationof the to-be-migrated UE in the DB server in step 107. Therefore,details are not described herein again.

In addition, similar to step 108, in step 209, to migrate theto-be-migrated UE to the destination controller in the second controldomain to implement load migration, the destination controller furtherneeds to send the inter-domain update instruction to the externalnetwork element, where the inter-domain update instruction includes theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the external network element receivingthe inter-domain update instruction establishes the correspondencebetween the to-be-migrated UE and the destination controller.

In this way, after the external network element receives the userrequest of the to-be-migrated UE subsequently, a correspondence betweenthe to-be-migrated UE and the source controller has been changed to thecorrespondence between the to-be-migrated UE and the destinationcontroller. Therefore, the external network element can forward the userrequest to the destination controller based on the foregoing changedcorrespondence, so that the destination controller replaces the sourcecontroller to process the user request, thereby implementing a loadmigration process across control domains.

Optionally, similar to step 109 to step 111, still as shown in FIG. 6,after step 209 is performed, the destination controller may furtherperform step 210 to step 212.

210. The destination controller allocates a destination session index tobe used in the second control domain to the to-be-migrated UE, that is,allocates a new session index to the to-be-migrated UE.

211. The destination controller sends a session index update instructionto the external network element, where the session index updateinstruction carries the newly allocated destination session index, sothat the external network element updates a stored session index of theto-be-migrated UE to the destination session index.

212. The destination controller sends an NES update instruction to adestination NES, where the NES update instruction also carries theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the destination NES establishes thecorrespondence between the to-be-migrated UE and the destinationcontroller.

In this way, by performing step 207 to step 212, the destinationcontroller has migrated the to-be-migrated UE that originally belongs tothe first control domain to the second control domain. Subsequently, theuser request initiated by the to-be-migrated UE is to be processed bythe destination controller in the second control domain. Different fromEmbodiment 1 in which the load migration process is performed by thesource controller, the load migration process in step 207 to step 212 isperformed by the destination controller. This is because a sourcecontroller needing to perform load migration usually has a very largeload value. To prevent a further increase in a communication delaycaused by a further increase in the load value of the source controller,the load migration process may be performed by a destination controllerhaving a relatively small load value.

Steps performed by the source controller in step 201 to step 212 may beimplemented by the source controller by executing the programinstruction stored in the memory 13 and executed by the processor 11 inFIG. 4. Similarly, steps performed by the destination controller in step201 to step 212 may be implemented by the destination controller byexecuting the program instruction stored in the memory 13 and executedby the processor 11 in FIG. 4.

Embodiment 3

This embodiment of the present disclosure provides a load migrationmethod. When load of a first control domain is relatively high, a sourcecontroller in the first control domain may actively migrate ato-be-migrated UE (where the to-be-migrated UE includes one or more UEs)in batches to a second control domain having relatively low load. Asshown in FIG. 7, the load migration method includes the following steps.

301. A migration scheduler obtains a load value of each controller ineach control domain.

302. If a first load value of the first control domain is greater than afirst load threshold, the source controller determines a quantity ofcandidate UEs that need to be migrated in the first control domain.

303. The source controller sends a migration request to the migrationscheduler, where the migration request carries the quantity of candidateUEs.

304. The migration scheduler determines, in the second control domainbased on a load value of each controller in the second control domainand the migration request, N (where N is a natural number) destinationcontrollers that are allowed to accept the candidate UEs, and determinesa quantity of candidate UEs that each destination controller is allowedto accept.

305. The migration scheduler sends, to the source controller,identifiers of the N destination controllers and the quantity ofcandidate UEs that each destination controller is allowed to accept.

306. The source controller determines, in the candidate UEs for eachdestination controller, the to-be-migrated UE corresponding to thedestination controller.

307. The source controller updates resource information of theto-be-migrated UE in a DB server, where the updated resource informationincludes a correspondence between the to-be-migrated UE and thedestination controller.

308. The source controller sends an inter-domain update instruction tothe external network element, where the inter-domain update instructionincludes an identifier of the to-be-migrated UE and an identifier of thedestination controller.

In this way, in the load migration method provided in this embodiment ofthe present disclosure, when the load of the first control domain isrelatively high, the source controller in the first control domain mayactively migrate the to-be-migrated UE in batches to the second controldomain having relatively low load. First, when the load value of thefirst control domain is relatively large, the source controller sends,to the migration scheduler, the migration request carrying a list ofcandidate UEs. The migration scheduler determines, for the sourcecontroller, the N candidate UEs (that is, the to-be-migrated UE) thatcan be migrated and the destination controller. Then, the sourcecontroller updates the resource information of the to-be-migrated UE inthe DB server. The updated resource information reflects thecorrespondence between the to-be-migrated UE and the destinationcontroller. In addition, the source controller further needs to send theinter-domain update instruction to the external network element. Theinter-domain update instruction is used to instruct the external networkelement to establish the correspondence between the to-be-migrated UEand the destination controller. In this way, after receiving a userrequest of the to-be-migrated UE subsequently, the external networkelement can forward the user request to the destination controller basedon the correspondence, so that the destination controller replaces thesource controller to process the user request, to implement a loadmigration process across control domains, thereby reducing acommunication delay generated due to overload of a current controldomain, and realizing resource sharing and coordination across thecontrol domains.

For example, in step 301, because the migration scheduler may establisha data connection to each controller in each control domain, themigration scheduler can obtain a load value of each controller in eachcontrol domain. That is, the migration scheduler may monitor a loadstatus of each controller in each control domain in real time.

A controller or a network element selector in each control domain canobtain a load status of only the domain. Therefore, when the first loadvalue of the first control domain is greater than the first loadthreshold, it indicates that the first control domain is overloaded. Inthis case, in step 302, any controller in the first control domain, forexample, a controller having a largest load value, that is, the sourcecontroller, determines the quantity of candidate UEs that need to bemigrated in the first control domain.

It may be understood that, a person skilled in the art may determine,based on actual experience or a particular algorithm, the candidate UEsthat need to be migrated, for example, may use one or more UEs having arelatively high activity level as the candidate UEs.

Then, in step 303, the source controller adds the quantity of candidateUEs to the migration request, and sends the migration request to themigration scheduler.

Optionally, the source controller may further adds identifiers of thecandidate UEs to the migration request, and sends the migration requestto the migration scheduler.

In this case, in step 304, after receiving the migration request, themigration scheduler may calculate a load value of each other controldomain than the first control domain based on the load value of eachcontroller in each control domain. When a load value of a controldomain, for example, the second control domain, is relatively small, Ndestination controllers that can accept the load migration in the secondcontrol domain and a quantity of candidate UEs that can be accepted byeach destination controller may further be determined based on the loadvalue of each controller in the second control domain.

For example, load values of a controller A and a controller B in thesecond control domain are relatively small. In this case, a quantity ofcandidate UEs that can be accepted by the controller A may be determinedbased on the load value of the controller A, and a quantity of candidateUEs that can be accepted by the controller B may be determined based onthe load value of the controller B.

Then, in step 305, the migration scheduler sends, to the sourcecontroller, the identifiers of the N destination controllers and thequantity of candidate UEs that can be accepted by each destinationcontroller.

It can be learned that, compared with Embodiment 1 and Embodiment 2 inwhich the migration scheduler actively sends the migration permissionmessage to the source controller to enable the load migration process,in this embodiment, the migration scheduler may further receive themigration request actively sent by the source controller, to trigger themigration scheduler to allocate an appropriate destination controller tothe source controller, to enable the load migration process.

In step 306, after receiving the identifiers of the N destinationcontrollers, and the quantity of candidate UEs that can be accepted byeach destination controller, the source controller determines, in thecandidate UEs for each destination controller based on the quantity ofcandidate UEs that can be accepted by each destination controller, oneor more to-be-migrated UEs corresponding to the destination controller,so that subsequently each to-be-migrated UE is migrated to acorresponding destination controller in the second control domain.

It can be learned that the process of determining the to-be-migrated UEin step 301 to step 306 does not need to be performed as in Embodiment 1or Embodiment 2 in which when the UE initiates the user request to thesource controller, whether each UE sending the user request isto-be-migrated UE is determined and the load migration is performed oneach to-be-migrated UE. In this embodiment, the source controller mayactively determine the to-be-migrated UE requiring load migration. Inthis way, there may be a plurality of to-be-migrated UEs. In this case,the source controller may migrate the plurality of UEs to anothercontrol domain at a time, thereby quickly reducing load pressure of thesource controller.

Further, similar to step 107, in step 307, the source controller updatesthe resource information of the to-be-migrated UE in the DB server. Theupdated resource information includes the correspondence between theto-be-migrated UE and the destination controller.

In addition, similar to step 108, in step 308, the source controllersends the inter-domain update instruction to the external networkelement, where the inter-domain update instruction includes theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the external network element establishesthe correspondence between the to-be-migrated UE and the destinationcontroller.

Optionally, similar to step 109 to step 111, still as shown in FIG. 7,after step 308 is performed, the source controller may further performstep 309 to step 311.

309. The source controller allocates a destination session index to beused in the second control domain to the to-be-migrated UE.

310. The source controller sends a session index update instruction tothe external network element, where the session index update instructioncarries the newly allocated destination session index, so that theexternal network element updates a stored session index of theto-be-migrated UE to the destination session index.

311. The source controller sends an NES update instruction to adestination NES, where the NES update instruction also carries theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the destination NES establishes thecorrespondence between the to-be-migrated UE and the destinationcontroller.

Steps performed by the source controller in step 301 to step 311 may beimplemented by the source controller by executing the programinstruction stored in the memory 13 and executed by the processor 11 inFIG. 4. Similarly, steps performed by the destination controller in step301 to step 311 may be implemented by the destination controller byexecuting the program instruction stored in the memory 13 and executedby the processor 11 in FIG. 4.

Embodiment 4

This embodiment of the present disclosure provides a load migrationmethod. When load of a first control domain is relatively high, adestination controller in a second control domain having relatively lowload may migrate to-be-migrated UE (where the to-be-migrated UE includesat least one UE) in batches. As shown in FIG. 8, the load migrationmethod includes the following steps.

401. A migration scheduler obtains a load value of each controller ineach control domain.

402. If a first load value of the first control domain is greater than afirst load threshold, a source controller determines a list of candidateUEs that need to be migrated in the first control domain.

403. The source controller sends a migration request to the migrationscheduler, where the migration request includes the list of candidateUEs.

404. If a second load value of the second control domain is less than asecond load threshold, the migration scheduler uses, as the destinationcontroller, a controller in the second control domain that is allowed toaccept candidate UE in the list of candidate UEs.

405. The migration scheduler forwards the migration request to thedestination controller, where the migration request carries the list ofcandidate UEs.

406. The destination controller determines to-be-migrated UE in thereceived list of candidate UEs.

407. The destination controller updates resource information of theto-be-migrated UE in a DB server based on an identifier of theto-be-migrated UE, where the updated resource information includes acorrespondence between the to-be-migrated UE and the destinationcontroller.

408. The destination controller sends an inter-domain update instructionto an external network element, where the inter-domain updateinstruction includes the identifier of the to-be-migrated UE and anidentifier of the destination controller.

In this way, in the load migration method provided in this embodiment ofthe present disclosure, when the load of the first control domain isrelatively high, the destination controller in the second control domainhaving relatively low load may actively migrate the to-be-migrated UE inbatches to the second control domain. First, when the load value of thefirst control domain is relatively high, the source controller sends, tothe migration scheduler, the migration request carrying the list ofcandidate UEs. After the migration scheduler forwards the migrationrequest to the corresponding destination controller, the destinationcontroller determines the to-be-migrated UE in the list of candidateUEs. Then, the destination controller updates the resource informationof the to-be-migrated UE in the DB server. The updated resourceinformation includes the correspondence between the to-be-migrated UEand the destination controller. In addition, the destination controllerfurther needs to send the inter-domain update instruction to theexternal network element, so that the external network elementestablishes the correspondence between the to-be-migrated UE and thedestination controller. In this way, after receiving a user request ofthe to-be-migrated UE subsequently, the external network element canforward the user request to the destination controller based on thecorrespondence, so that the destination controller replaces the sourcecontroller to process the user request, to implement a load migrationprocess across control domains, thereby reducing a communication delaygenerated due to overload of a current control domain, and realizingresource sharing and coordination across the control domains.

Similar to step 301 to step 303, in step 401 to step 403, the migrationscheduler obtains the load value of each controller in each controldomain. If the first load value of the first control domain is greaterthan the first load threshold, the source controller determines the listof candidate UEs that need to be migrated in the first control domain.Then, the source controller sends the migration request to the migrationscheduler, where the migration request includes the list of candidateUEs.

In this case, in step 404, after receiving the migration request, themigration scheduler may calculate a load value of each other controldomain than the first control domain based on the load value of eachcontroller in each control domain. When a load value of a control domain(for example, the second control domain) is relatively small, acontroller in the second control domain that can accept the candidate UEin the list of candidate UEs may further be determined as thedestination controller based on the load value of each controller in thesecond control domain, that is, determining the destination controllerthat can receive the migration request.

Herein, the migration scheduler may determine a plurality of destinationcontrollers.

Then, in step 405, the migration scheduler forwards the migrationrequest to the determined destination controller. The migration requestcarries the list of candidate UEs. The list of candidate UEs may includean identifier of each candidate UE.

In this way, after receiving the migration request, the destinationcontroller may determine the to-be-migrated UE in the received list ofcandidate UEs.

For example, the destination controller may select one or more UEs inthe list of candidate UEs as the to-be-migrated UE based on a load valueof the destination controller.

Then, similar to step 307 and step 308, in step 407 and step 408, thedestination controller updates the resource information of theto-be-migrated UE in the DB server based on the identifier of theto-be-migrated UE. The updated resource information includes thecorrespondence between the to-be-migrated UE and the destinationcontroller. In addition, the destination controller sends theinter-domain update instruction to the external network element, wherethe inter-domain update instruction includes the identifier of theto-be-migrated UE and the identifier of the destination controller, sothat the external network element receiving the inter-domain updateinstruction establishes the correspondence between the to-be-migrated UEand the destination controller.

Optionally, similar to step 109 to step 111, still as shown in FIG. 8,after step 408 is performed, the destination controller may furtherperform step 409 to step 411.

409. The destination controller allocates a destination session index tobe used in the second control domain to the to-be-migrated UE.

410. The destination controller sends a session index update instructionto the external network element, where the session index updateinstruction carries the newly allocated destination session index, sothat the external network element updates a stored session index of theto-be-migrated UE to the destination session index.

411. The destination controller sends an NES update instruction to adestination NES, where the NES update instruction also carries theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the destination NES establishes thecorrespondence between the to-be-migrated UE and the destinationcontroller.

Different from Embodiment 3 in which the load migration process isperformed by the source controller, the load migration process in step407 to step 411 is performed by the destination controller. This isbecause a source controller needing to perform load migration usuallyhas a very large load value. To prevent a further increase in acommunication delay caused by a further increase in the load value ofthe source controller, the load migration process may be performed by adestination controller having a relatively small load value.

Steps performed by the source controller in step 401 to step 411 may beimplemented by the source controller by executing the programinstruction stored in the memory 13 and executed by the processor 11 inFIG. 4. Similarly, steps performed by the destination controller in step401 to step 411 may be implemented by the destination controller byexecuting the program instruction stored in the memory 13 and executedby the processor 11 in FIG. 4.

It can be learned from Embodiment 1 to Embodiment 4 that, theembodiments of the present disclosure provide two load migrationmethods.

In the load migration method 1, as shown in Embodiment 1 or Embodiment3, the source controller actively migrates the to-be-migrated UE to thedestination controller (where the source controller is located in thefirst control domain, and the destination controller is located in thesecond control domain).

First, the source controller may interact with the migration schedulerto determine the destination controller accepting the load migration.Then, the source controller determines the to-be-migrated UE that needsto be migrated to the destination controller. For example, when the loadvalue of the first control domain is relatively large, and the loadvalue the second control domain is relatively small, the sourcecontroller may use the UE indicated by the newly received user requestas the to-be-migrated UE.

The DB server stores the resource information such as the subscriptiondata and the context data of the to-be-migrated UE, and the subscriptiondata and the context data reflect the correspondence between theto-be-migrated UE and the source controller. Therefore, to migrate theto-be-migrated UE to the destination controller in the second controldomain, the source controller may update the resource information of theto-be-migrated UE in the DB server, to establish the correspondencebetween the to-be-migrated UE and the destination controller in thesubscription data and the context data of the to-be-migrated UE.

In addition, the external network element originally stores thecorrespondence between the to-be-migrated UE and the source controller.After receiving the user request of the to-be-migrated UE, the externalnetwork element forwards the user request to the source controller basedon the correspondence. Therefore, the source controller further needs tosend the inter-domain update instruction to the external networkelement, where the inter-domain update instruction includes theidentifier of the to-be-migrated UE and the identifier of thedestination controller, so that the external network element establishesthe correspondence between the to-be-migrated UE and the destinationcontroller.

In this way, after the external network element receives the userrequest of the to-be-migrated UE subsequently, the controller in thecorrespondence has been changed to the destination controller.Therefore, the external network element can forward the user request tothe destination controller based on the correspondence, so that thedestination controller replaces the source controller to process theuser request, thereby implementing the load migration process across thecontrol domains.

In the load migration method 2, as shown in Embodiment 2 or Embodiment4, when the load value of the first control domain is relatively large,and the load value of the second control domain is relatively small, thedestination controller in the second control domain may migrate theto-be-migrated UE originally belonging to the first control domain tothe second control domain.

First, when the load value of the first control domain is relativelylarge, and the load value of the second control domain is relativelysmall, the destination controller may obtain the migration request sentby the source controller. The migration request carries the identifierof the to-be-migrated UE.

Then, the destination controller updates the resource information of theto-be-migrated UE in the DB server based on the identifier of theto-be-migrated UE. The updated resource information includes thecorrespondence between the to-be-migrated UE and the destinationcontroller.

In addition, the destination controller further needs to send theinter-domain update instruction to the external network element, wherethe inter-domain update instruction includes the identifier of theto-be-migrated UE and the identifier of the destination controller, sothat the external network element establishes the correspondence betweenthe to-be-migrated UE and the destination controller. In this way, afterthe external network element receives the user request of theto-be-migrated UE subsequently, the external network element can forwardthe user request to the destination controller based on thecorrespondence, so that the destination controller replaces the sourcecontroller to process the user request, thereby implementing the loadmigration process across the control domains.

Further, FIG. 9 is a schematic structural diagram of a source controlleraccording to an embodiment of the present disclosure. The sourcecontroller provided in this embodiment of the present disclosure may beconfigured to implement the methods implemented in the embodiments ofthe present disclosure shown in FIG. 2 to FIG. 8. For ease ofdescription, only a part related to this embodiment of the presentdisclosure is shown. For specific technical details that are notdisclosed, refer to the embodiments of the present disclosure shown inFIG. 2 to FIG. 8.

Specifically, the source controller includes a determining unit 31,configured to determine to-be-migrated UE that needs to be migrated to adestination controller, where the destination controller is a controllerin a second control domain, an update unit 32, configured to updateresource information of the to-be-migrated UE in a database server,where the updated resource information includes a correspondence betweenthe to-be-migrated UE and the destination controller, and the databaseserver is connected to both the source controller and the destinationcontroller, and a sending unit 33, configured to send an inter-domainupdate instruction to an external network element, where theinter-domain update instruction includes an identifier of theto-be-migrated UE and an identifier of the destination controller.

Further, still as shown in FIG. 9, the source controller furtherincludes an obtaining unit 34.

The obtaining unit 34 is configured to receive a list of candidatecontrollers in the second control domain that is sent by a migrationscheduler, and receive a user request sent by first UE, where the sourcecontroller is a controller in the first control domain that receives theuser request.

In this case, the determining unit 31 is specifically configured todetermine whether to use the first UE as the to-be-migrated UE if theuser request of the first UE is received, and determine a candidatecontroller in the list of candidate controllers as the destinationcontroller if determining that the first UE is used as theto-be-migrated UE.

Further, still as shown in FIG. 9, the obtaining unit 34 is furtherconfigured to obtain at least one of location information of the firstUE, a priority of the user request, and a type of a service requested bythe first UE.

The determining unit 31 is specifically configured to determine, basedon at least one of the obtained location information of the first UE,priority of the user request, and type of the service, whether to usethe first UE as the to-be-migrated UE.

Alternatively, still as shown in FIG. 9, the sending unit 33 is furtherconfigured to send, to a migration scheduler, a quantity of candidateUEs that need to be migrated, so that the migration schedulerdetermines, in the second control domain, N destination controllers thatare allowed to accept the candidate UEs, and determines a quantity ofcandidate UEs that each destination controller is allowed to accept,where N is a natural number.

The obtaining unit 34 is configured to receive, from the migrationscheduler, identifiers of the N destination controllers and the quantityof candidate UEs that each destination controller is allowed to accept.

The determining unit 31 is specifically configured to determine, in thecandidate UEs for each destination controller, to-be-migrated UE thatthe destination controller is allowed to accept.

Further, the update unit 32 is specifically configured to search thedatabase server for subscription data and context data of theto-be-migrated UE based on the identifier of the to-be-migrated UE,reallocate a user identifier to the to-be-migrated UE, and update, inthe subscription data and the context data, the identifier of theto-be-migrated UE to the reallocated user identifier, and update astored identifier of the source controller to the identifier of thedestination controller.

Further, still as shown in FIG. 9, the source controller furtherincludes an allocation unit 35, configured to allocate a destinationsession index to be used in the second control domain to theto-be-migrated UE, where the destination session index is used toindicate a session identifier of a session between the to-be-migrated UEand the destination controller.

In this case, the sending unit 34 is further configured to send asession index update instruction to the external network element, wherethe session index update instruction includes the destination sessionindex.

Further, the sending unit 34 is further configured to send a networkelement selector NES update instruction to a destination NES, where theNES update instruction includes the identifier of the to-be-migrated UEand the identifier of the destination controller.

In this embodiment of the present disclosure, specific functions of theobtaining unit 34 and the sending unit 33 in the source controller maybe implemented by the processor 11 in the computer device wo shown inFIG. 4 by invoking the transceiver 14, and specific functions of thedetermining unit 31, the update unit 32, and the allocation unit 35 inthe source controller may be implemented by the processor 11 in thecomputer device wo in FIG. 4 by invoking the application program codestored in the memory 13 for performing the solutions of the presentdisclosure.

FIG. 10 is a schematic structural diagram of a destination controlleraccording to an embodiment of the present disclosure. The destinationcontroller provided in this embodiment of the present disclosure may beconfigured to implement the methods implemented in the embodiments ofthe present disclosure shown in FIG. 2 to FIG. 8. For ease ofdescription, only a part related to this embodiment of the presentdisclosure is shown. For specific technical details that are notdisclosed, refer to the embodiments of the present disclosure shown inFIG. 2 to FIG. 8.

Specifically, the destination controller includes an obtaining unit 41,configured to obtain a migration request sent by a source controller,where the migration request carries an identifier of to-be-migrated UE,the source controller is a controller in a first control domain, and thedestination controller is a controller in a second control domain, anupdate unit 42, configured to update resource information of theto-be-migrated UE in a database server based on the identifier of theto-be-migrated UE, where the updated resource information includes acorrespondence between the to-be-migrated UE and the destinationcontroller, and the database server is connected to both the sourcecontroller and the destination controller, and a sending unit 43,configured to send an inter-domain update instruction to an externalnetwork element, where the inter-domain update instruction includes theidentifier of the to-be-migrated UE and an identifier of the destinationcontroller.

Further, still as shown in FIG. 10, the destination controller furtherincludes a determining unit 44.

The obtaining unit 41 is specifically configured to receive a migrationrequest forwarded by a migration scheduler, where the migration requestcarries a list of candidate UEs that need to be migrated in the firstcontrol domain, and the list of candidate UEs includes an identifier ofeach candidate UE that needs to be migrated.

The determining unit 44 is configured to determine the to-be-migrated UEin the list of candidate UEs.

In this embodiment of the present disclosure, specific functions of theobtaining unit 41 and the sending unit 43 in the destination controllermay be implemented by the processor 11 in the computer device 100 shownin FIG. 4 by invoking the transceiver 14, and specific functions of thedetermining unit 44 and the update unit 42 in the destination controllermay be implemented by the processor 11 in the computer device 100 inFIG. 4 by invoking the application program code stored in the memory 13for performing the solutions of the present disclosure.

In this way, in load migration apparatuses provided in this embodimentof the present disclosure, when the load of the first control domain isrelatively high, the destination controller in the second control domainhaving relatively low load may actively migrate the to-be-migrated UE inbatches to the second control domain. First, when the load value of thefirst control domain is relatively high, the source controller sends, tothe migration scheduler, the migration request carrying the list ofcandidate UEs. After the migration scheduler forwards the migrationrequest to the corresponding destination controller, the destinationcontroller determines the to-be-migrated UE in the list of candidateUEs. Then, the destination controller updates the resource informationof the to-be-migrated UE in the DB server. The updated resourceinformation reflects the correspondence between the to-be-migrated UEand the destination controller. In addition, the destination controllerfurther needs to send the inter-domain update instruction to theexternal network element, where the inter-domain update instruction isused to instruct the external network element to establish thecorrespondence between the to-be-migrated UE and the destinationcontroller. In this way, after receiving the user request of theto-be-migrated UE subsequently, the external network element can forwardthe user request to the destination controller based on thecorrespondence, so that the destination controller replaces the sourcecontroller to process the user request, to implement a load migrationprocess across control domains, thereby reducing a communication delaygenerated due to overload of a current control domain, and realizingresource sharing and coordination across the control domains.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, descriptions are madeby using only division into the foregoing functional modules as anexample. In actual application, the foregoing functions can be allocatedto different functional modules for implementation depending onrequirements. In other words, an inner structure of an apparatus isdivided into different functional modules to implement all or some ofthe functions described above. For a detailed working process of theforegoing system, apparatus, and unit, refer to a corresponding processin the foregoing method embodiments, and details are not describedherein.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is only an example. For example, the module or unit divisionis only logical function division and may be other division duringactual implementation. For example, a plurality of units or componentsmay be combined or integrated into another system, or some features maybe ignored or not performed. In addition, the displayed or discussedmutual couplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualneeds to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of the presentdisclosure may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of a software functional unit.

When the integrated unit is implemented in the form of a softwarefunctional unit and sold or used as an independent product, theintegrated unit may be stored in a computer readable storage medium.Based on such an understanding, the technical solutions of the presentdisclosure essentially, or the part contributing to the prior art, orall or a part of the technical solutions may be implemented in the formof a software product. The software product is stored in a storagemedium and includes several instructions for instructing a computerdevice (which may be a personal computer, a server, a network device, orthe like) or a processor to perform all or a part of the steps of themethods described in the embodiments of the present disclosure. Theforegoing storage medium includes any medium that can store programcode, such as a USB flash drive, a removable hard disk, a read-onlymemory (ROM), a random access memory (RAM), a magnetic disk, or anoptical disc.

The descriptions are only specific implementations of the presentdisclosure, but are not intended to limit the protection scope of thepresent disclosure. Any variation or replacement readily figured out bya person skilled in the art within the technical scope disclosed in thepresent disclosure shall fall within the protection scope of the presentdisclosure. Therefore, the protection scope of the present disclosureshall be subject to the protection scope of the claims.

What is claimed is:
 1. A method, comprising: obtaining, by a firstcontroller, a first temporary user identifier of a user equipment (UE),the first temporary user identifier comprising a second identifier of asecond controller; allocating, by the first controller, a secondtemporary user identifier to the UE, the second temporary useridentifier comprising a first identifier of the first controller;transmitting, by the first controller, the second temporary useridentifier to a database server for updating the first temporary useridentifier by the second temporary user identifier; and sending, by thefirst controller to an external network element, the first identifier ofthe first controller.
 2. The method according to claim 1, whereinobtaining the first temporary user identifier comprises: receiving, bythe first controller, a request from a migration scheduler, the requestcomprising the first temporary user identifier of the UE.
 3. The methodaccording to claim 2, wherein the migration scheduler is integrated intoa base station.
 4. The method according to claim 1, wherein the firstcontroller and the second controller are located in two differentcontrol domains.
 5. The method according to claim 4, wherein a firstdomain of the first controller has a shared load that is lower than ashared load of a second domain of the second controller.
 6. Anapparatus, comprising: a receiver; a transmitter, a processor; and anon-transitory computer readable medium having a program stored thereonfor execution by the processor, the program including instructions to:obtain, through the receiver, a first temporary user identifier of auser equipment (UE), the first temporary user identifier comprising asecond identifier of a second controller; allocate a second temporaryuser identifier to the UE, the second temporary user identifiercomprising a first identifier of a first controller; cause thetransmitter to transmit the second temporary user identifier to adatabase server for updating the first temporary user identifier by thesecond temporary user identifier; and cause the transmitter to transmitthe first identifier of the first controller to an external networkelement.
 7. The apparatus according to claim 6, wherein the programfurther includes instructions to receive, through the receiver, arequest from a migration scheduler, the request comprising the firsttemporary user identifier of the UE.
 8. The apparatus according to claim7, wherein the migration scheduler is integrated in a base station. 9.The apparatus according to claim 6, wherein the first controller and thesecond controller are located in two different control domains.
 10. Theapparatus according to claim 9, wherein a first domain of the firstcontroller has a shared load that is lower than a shared load of asecond domain of the second controller.
 11. The apparatus according toclaim 6, wherein the apparatus is the first controller.
 12. A method,comprising: obtaining, by a database server, a first temporary useridentifier of a user equipment (UE), the first temporary user identifiercomprising an second identifier of a second controller; receiving, bythe database server, a second temporary user identifier from a firstcontroller, the second temporary user identifier comprising a firstidentifier of the first controller; replacing, by the database server,the first temporary user identifier by the second temporary useridentifier, the database server being connected to both the firstcontroller and the second controller.
 13. The method according to claim12, wherein replacing the first temporary user identifier comprises:searching, by the database server, context data of the UE based on thefirst temporary user identifier of the UE; and replacing, by thedatabase server, the first temporary user identifier by the secondtemporary user identifier in the context data.
 14. The method accordingto claim 12, wherein the first controller and the second controller arelocated in two different control domains.
 15. The method according toclaim 14, wherein a first domain of the first controller has a sharedload that is lower than a shared load of a second domain of the secondcontroller.
 16. An apparatus, comprising: a receiver; a processor; and anon-transitory computer readable medium having a program stored thereonfor execution by the processor, the program having instructions to:obtain, a first temporary user identifier of a user equipment (UE), thefirst temporary user identifier comprising a second identifier of asecond controller; receive, through the receiver, a second temporaryuser identifier from a first controller, the second temporary useridentifier comprising a first identifier of the first controller; andreplace the first temporary user identifier by the second temporary useridentifier.
 17. The apparatus according to claim 16, wherein theinstructions to replace the first temporary user identifier by thesecond temporary user identifier include instructions to: search contextdata of the UE according to the first temporary user identifier of theUE; and replace the first temporary user identifier by the secondtemporary user identifier in the context data.
 18. The apparatusaccording to claim 16, wherein the first controller and the secondcontroller are located in two different control domains.
 19. Theapparatus according to claim 18, wherein a first domain of the firstcontroller has a shared load that is lower than a shared load of asecond domain of the second controller.
 20. The apparatus according toclaim 16, wherein the apparatus is a database server connected to boththe first controller and the second controller.